Lesson Title: Using Percent Composition as a Conversion Factor
State Standards: GLEs/GSEs
PS2 (Ext)-6
Students demonstrate an understanding of physical, chemical, and nuclear changes by... 6aa-using chemical equations and information about molar masses to predict quantitatively the masses of reactants and products in chemical reactions.
National Standards:
Context of Lesson:
This is a 90 minute lesson in which students will explore how to use percent composition as a conversion factor. This concept will be worked with using practice examples and problems. Provided that there is ample time, this concept will be reinforced by completing Part II of the laboratory exercise.
Opportunities to Learn:
Depth of Knowledge
Can you estimate what DOKs you will address here?
Prerequisite Knowledge
Percent composition
Plans for Differentiating Instruction
If students are having trouble with calculating percent composition try giving them a number of mathematical examples involving calculating percents. When will this happen?
Accommodations and modifications
Environmental factors
There is a smartboard which will be used for practice examples and problems. Desk are in rows.
Materials
Students will need their required materials (textbook, notebook, calculator, pen/pencil)
Refer to Part II of the laboratory exercise (Making Cents out of Penny Composition) for a list of materials needed
Objectives:
Students will practice using percent composition as a conversion factor. Is this really all? Should they be able to explain what their doing and why it might be useful?
Instruction:
Opening:
Pose the following questions after explaining to students that they will be starting Part II of the laboratory exercise: Why were some of the masses of the pennies different from one another? Does it matter which mint the pennies came from? Does the date they were minted have anything to do with the masses being different? Be sure to collect, check, and hand back the worksheet assigned in the previous class. The beginning of the period will be spent going over the worksheet with ample time for questions. After the worksheet has been gone over begin the lesson. This doesn't make sense here. Have they done anything with pennies yet?
Engagement:
Today we are going to take the idea of percent composition a step further.
We can use the percent composition to calculate the number of grams of a particular element contained in a specific amount of a compound. Why would we want to do this? Is there a way to continue with your fertilizer example?
So, if we wanted to know the mass of C in 82.0 g of propane (C3H8) we would need to convert grams of C3H8 to grams of C. What do we need to do first? Answer: Determine the percent composition of C in C3H8. %C = 36.0 g C/44.0 g C3H8 x 100% = 81.8% C Your language implies that determining the mass of the Carbon is just a conversion process. Is this true. It sounds like it is inconsistent with conservation of mass, since the H is disappearing.
So, we can say that the ratio of C to C3H8 is 81.8 g C per 100.0g C3H8. This is our conversion factor: 81.8 g C/100.0 g C3H8. Our linear conversion will look like this: 82.0 C3H8 x 81.8 g C/100.0 g C3H8 = 67.1 g C Is there a way to have students try to figure out how to do this before you show them?
Assign the following practice problems:
Using the same idea as the previous example, calculate the mass of hydrogen in each of the following:
350 g C2H6
20.2 g NaHSO4
2.14 g NH4Cl
Now, let's revisit our fertilizer example: Calculate the grams of nitrogen in 125 g of each fertilizer.
CO(NH2)2
NH3
NH4NO3
Students will be asked to put these problems up on the board and briefly explain their solutions.
Continue the lesson by introducing Part II of the laboratory exercise: Making Cents of Penny Composition. Part II requires mainly calculation so if time is a constraint after an explanation of what students should be doing, calculations can potentially be finished for homework. Where was part I? Did I miss it?
Closure:
End the lesson by going over the results obtained from calculation performed in Part II of the laboratory exercise. Explain that the following class will be spent learning how to obtain empirical and molecular formulas. Give students a brief preview if time permits. Assign reading in section 7.3 for homework: Calculating Empirical Formulas, Calculating Molecular Formulas on pp. 192-194. Advise students that they should focus on the following concepts:
The definition of an empirical formula and how it is calculated.
How we calculate molecular formulas from the compound's empirical formula and molar mass.
Explain to students that they will be having a brief quiz on the reading and that their finished data sheets for Part II of the Laboratory exercise will also be due. Nice pre-reading strategy. How about offering 1 pt EC on quiz for one page of reading notes summarizing conversion process?
Assessment:
Students will be assessed formatively on their ability to use percent composition as a conversion factor by being asked to explain their solutions to the practice problems. They will be quizzed on the material that they were assigned to read (the quiz will be mainly conceptual not involving very much calculation or math). The data sheets will be used as an artifact monitoring student's ability to practically apply what they have learned.
Lesson Plan
Lesson Title: Using Percent Composition as a Conversion Factor
State Standards: GLEs/GSEs
PS2 (Ext)-6Students demonstrate an understanding of physical, chemical, and nuclear changes by...
6aa-using chemical equations and information about molar masses to predict quantitatively the masses of reactants and products in chemical reactions.
National Standards:
Context of Lesson:
This is a 90 minute lesson in which students will explore how to use percent composition as a conversion factor. This concept will be worked with using practice examples and problems. Provided that there is ample time, this concept will be reinforced by completing Part II of the laboratory exercise.Opportunities to Learn:
Depth of Knowledge
Can you estimate what DOKs you will address here?Prerequisite Knowledge
Plans for Differentiating Instruction
If students are having trouble with calculating percent composition try giving them a number of mathematical examples involving calculating percents. When will this happen?Accommodations and modifications
Environmental factors
There is a smartboard which will be used for practice examples and problems. Desk are in rows.Materials
Objectives:
Students will practice using percent composition as a conversion factor.Is this really all? Should they be able to explain what their doing and why it might be useful?
Instruction:
Opening:
Pose the following questions after explaining to students that they will be starting Part II of the laboratory exercise: Why were some of the masses of the pennies different from one another? Does it matter which mint the pennies came from? Does the date they were minted have anything to do with the masses being different? Be sure to collect, check, and hand back the worksheet assigned in the previous class. The beginning of the period will be spent going over the worksheet with ample time for questions. After the worksheet has been gone over begin the lesson. This doesn't make sense here. Have they done anything with pennies yet?Engagement:
Today we are going to take the idea of percent composition a step further.- We can use the percent composition to calculate the number of grams of a particular element contained in a specific amount of a compound. Why would we want to do this? Is there a way to continue with your fertilizer example?
- So, if we wanted to know the mass of C in 82.0 g of propane (C3H8) we would need to convert grams of C3H8 to grams of C. What do we need to do first? Answer: Determine the percent composition of C in C3H8. %C = 36.0 g C/44.0 g C3H8 x 100% = 81.8% C Your language implies that determining the mass of the Carbon is just a conversion process. Is this true. It sounds like it is inconsistent with conservation of mass, since the H is disappearing.
- So, we can say that the ratio of C to C3H8 is 81.8 g C per 100.0g C3H8. This is our conversion factor: 81.8 g C/100.0 g C3H8. Our linear conversion will look like this: 82.0 C3H8 x 81.8 g C/100.0 g C3H8 = 67.1 g C Is there a way to have students try to figure out how to do this before you show them?
Assign the following practice problems:Using the same idea as the previous example, calculate the mass of hydrogen in each of the following:
- 350 g C2H6
- 20.2 g NaHSO4
- 2.14 g NH4Cl
Now, let's revisit our fertilizer example: Calculate the grams of nitrogen in 125 g of each fertilizer.- CO(NH2)2
- NH3
- NH4NO3
Students will be asked to put these problems up on the board and briefly explain their solutions.Continue the lesson by introducing Part II of the laboratory exercise: Making Cents of Penny Composition. Part II requires mainly calculation so if time is a constraint after an explanation of what students should be doing, calculations can potentially be finished for homework. Where was part I? Did I miss it?
Closure:
End the lesson by going over the results obtained from calculation performed in Part II of the laboratory exercise. Explain that the following class will be spent learning how to obtain empirical and molecular formulas. Give students a brief preview if time permits. Assign reading in section 7.3 for homework: Calculating Empirical Formulas, Calculating Molecular Formulas on pp. 192-194. Advise students that they should focus on the following concepts:- The definition of an empirical formula and how it is calculated.
- How we calculate molecular formulas from the compound's empirical formula and molar mass.
Explain to students that they will be having a brief quiz on the reading and that their finished data sheets for Part II of the Laboratory exercise will also be due. Nice pre-reading strategy. How about offering 1 pt EC on quiz for one page of reading notes summarizing conversion process?Assessment:
Students will be assessed formatively on their ability to use percent composition as a conversion factor by being asked to explain their solutions to the practice problems. They will be quizzed on the material that they were assigned to read (the quiz will be mainly conceptual not involving very much calculation or math). The data sheets will be used as an artifact monitoring student's ability to practically apply what they have learned.Reflections
(only done after lesson is enacted)Student Work Sample 1 – Approaching Proficiency:
Student Work Sample 2 – Proficient:
Student Work Sample 3 – Exceeds Proficiency: